Domestic ice maker and defrost timer

ABSTRACT

A refrigeration apparatus having an automatic ice maker wherein defrosting of the apparatus is periodically effected as a function of the number of ice maker cycles. The ice maker may be allowed to dry cycle under full bin or shutoff conditions, and means may be provided to simulate an ice making operation condition to continue the cycling of the mechanism in the dry cycle mode. The control provides means for maintaining the defrosting operation for a preselected time to assure desired defrosting of the apparatus.

Linstromherg 45 D 24, 1974 [54] DOMESTIC ICE MAKER AND DEFROST 3,541,806 11/1970 Jacobs 62/233 TIMER 3,714,794 2/1973 Linstromberg (12/137 [75] Inventor: William J. Linstromberg, Evansville, Primary Examiner Meyer Perlin Attorney, Agent, or Firm-Hofgren, Wegner, Allen, [73] Assignee: Whirlpool Corporation, Benton Stellmall & MCCOfd Harbor, Mich. 221 Filed: Mar. 21, 1973 [57] ABSTRACT A refrigeration apparatus having an automatic ice [21] Appl' N05 343,281 maker wherein defrosting of the apparatus is periodically effected as a function of the number of ice [52] U.S. c1 62/135, 62/233, 62/234 maker cycles- The ice maker y be allowed to y 51 Int. Cl. rzsc 1/00 cycle under full bin or shutoff conditions, and means [58] Field of Search 62/233, 234, 135, 155 may be Provided to simulate an ice making Operation condition to continue the cycling of the mechanism in [5 References Cited the dry cycle mode. The control provides means for UNITED STATES PATENTS maintaining the defrosting operation for a preselected time to assure desired defrosting of the apparatus. 2,757,519 8/1956 Sampson 62/353 X 3,l43,863 8/1964 Nelson 62/72 10 Claims, 6 Drawing Figures 1 7' 7' a; 45 7 26 Ice Maker 5% Thermoslot 1 Ice Defrost Water Heater M3155; A251 vuwe PATENTED 953245174 3,855,812

I Thermostat Switch I PATENTEI] UEE24|974 3 y MM) 5 H a w 1 H 1 c a mm r L/J mm mm WV Condenser Fan Defrosr Heater DOMESTIC ICE MAKER AND DEFROST TIMER BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to refrigeration apparatus, and in particular, to means to controlling the defrosting of refrigeration apparatus.

2. Description of the Prior Art It has been conventional in refrigeration apparatus to provide a defrost timer mechanism adapted to effect at preselected intervals a defrosting of the cooling means of the refrigeration apparatus. In one form of refrigeration apparatus, an automatic ice maker is provided which makes a plurality of ice bodies and delivers them to a collecting bin in a harvesting operation in a cyclical repeated mode of operation. In such apparatus, a drive motor is conventionally provided to control the operation of the ice maker.

It is costly to provide separate time-controlled defrosting means and time-controlled ice maker means. In one improved form of ice maker disclosed and claimed in copending application Ser. No. 223,716, filed Feb. 4, 1972, means are provided for operating the defrost timing control from the ice maker mechanism drive motor.

It is further known to provide means for controlling the operation of the ice maker by selectively preventing delivery of water to the ice maker mold while maintaining the cyclical operation of the ice maker mechanism so as to cause the mechanism to go through dry ice making cycles such as when the collecting bin is full. One example of an ice maker apparatus providing such a water supply" control is that ofJ. K. Nelson, U.S. Letters Pat. No. 3,143,863.

In certain of the prior art devices, the ice maker drive motor is run continuously sothat, in effect, the drive motor becomes a clock which could be further used to provide the timing of the defrost cycles. It has been found desirable, however, to vary the defrosting intervals in accordance with the usage of the refrigeration apparatus. Thus, for example, where the apparatus comprises arefrigerator and the refrigerator is in substantial use so that the com pressor motor is actuated frequently to maintain the desired refrigeration temperature, a frequent defrosting ofthe apparatus may be desired. Where the apparatus, on the other hand, is not in constant use so that the refrigeration temperature is maintained with less operation of the compressor, the need for defrosting is correspondingly reduced and, thus, it is desirable to increase the interval between defrosting operations. One form of refrigeration apparatus, therefore, utilizes a defrost timing means which is actuated by timer means operated only during the operation of the compressor.

One example of refrigeration apparatus wherein the timing is effected only during compressor operation is shown in U.S. Pat. No. 3,312,080 of J. A. Dahlgren. In this patent, the refrigeration apparatus includes separate ice maker and defrost cycle timing means both of which are adapted to be operated only during compressor operation.

In one form of ice maker apparatus, the completion of the ice making cycle is sensed by a thermostat which is in thermal transfer association with the ice maker mold so as to terminate the ice body formation cycle when the mold temperature reaches a preselected low temperature. An excellent example of such an ice maker is shown in W. J. Linstromberg US. Pat. No. 3,276,225 for an Ice Cube Maker Having Motor Operated Ejector Fingers, owned by the assignee hereof, and incorporated by reference herein. Reference may be had to said patent for a complete disclosure of an ice maker mechanism and refrigeration apparatus associated therewith for effecting the cyclical formation and harvesting of the ice bodies.

SUMMARY OF THE INVENTION The present invention comprehends an improved refrigeration apparatus having an ice maker and means for cycling the ice maker to make successive batches of ice bodies wherein means are provided for defrosting the apparatus at preselected intervals corresponding to a preselected number of cycles of operation of the ice maker.

The apparatus may include thermostat means for controlling the cycling of the ice maker and means for cycling the ice maker at times without water delivered thereto to provide dry cycle operation thereof. In this form of the refrigeration apparatus, means are provided for operating the thermostat to simulate a normal ice making operation during the dry cycle operation to cause the preselected number of cycles to include such dry cycles.

The apparatus may include a mold in which ice bodies are formed and from which the ice bodies are harvested by suitable transferring means. The control may be arranged to effect defrosting of the apparatusonly during the harvesting cycles of operation.

The control includes means responsive to the preselected number of cycles for initiating operation of the defrosting means, and means for maintaining operation of the defrosting means for a preselected period of time to effect the desired defrosting of the cooling means. Thus, the invention comprehends the use of a single drive means in the form of a drive motor which operates the ice maker and which may be utilized to provide periodic energization of the defrost heater. The drive motor may take the form of a conventional timer motor. The motor need not run continuously but may be operated only during ice harvesting cycles or compressor operation periods, as desiredThe elimination of separate timer motors and timing mechanisms as used in the prior art permits a substantial reduction in the cost and bulk of the control mechanism and permits the assembly thereof in a simple, small housing. As the defrost cycle is related to the harvesting cycle, the ice body forming cycles, wherein the freezing of the ice bodies is effected, are independent of defrosting cycles and, thus, interruption of the ice making ,cycle is avoided, assuring that the ice bodies will be fully formed during each ice forming operation prior to the initiation of a harvesting cycle and/or a defrost cycle.

The drive motor may effect the desired duration of defrost operation by a suitable control of the defrost heater switch with the drive motor functioning as a clock. The control is effected by the simple addition of suitable gears and cams driven by the drive motor to control the defrost switches.

BRIEF DESCRIPTION OF THE DRAWING Other features and advantages of the invention will be apparent from the following description taken in connection with the accompanying drawing wherein:

FIG. 1 is a front perspective view of a refrigeration apparatus having a defrost timer control embodying the invention;

FIG. 2 is a schematic diagram of the electrical circuitry of the control;

FIG. 3 is a fragmentary front elevation of the timer control with the cover removed;

FIG. 4 is a fragmentary section illustrating the arrangement of the thermostat relative to the ice maker mold in one form of the invention;

FIG. 5 is a fragmentary front elevation of a modified form of timer control embodying the invention with the cover removed; and

FIG. 6 is a schematic diagram of the electrical circuitry of the modified form of ice maker of FIG. 5 adapted for use with the defrost control hereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the exemplary embodiment of the invention as shown in FIGS. 1-4 of the drawing, a refrigeration apparatus generally designated 10 is shown to include a cabinet 11 defining a freezer space 12 in which is mounted an ice maker mechanism 13 for cyclically forming and harvesting ice bodies. Cabinet 11 may further'define a refrigerator space 14. Refrigeration of spaces 12 and 14 may be effected by means of an evaporator 15 in the dividing wall 16 and rear wall 17 of the cabinet. The apparatus may include a conventional refrigerant fluid system including a compressor 18 which delivers compressed refrigerant through a condenser 19 and a capillary 20 to the evaporator 15. The compressor refrigerant expands in evaporator 15 to absorb heat from space 12. The expanded refrigerant is then passed through a return duct 21 to compressor 18 for recompression and recirculation to the evaporator in the conventional manner. A defrost heater 41 is provided in heat transfer association with at least a portion of the evaporator 15 in a conventional manner such as a serpentine heater pressed into the surface of the evaporator fins in the case of a tube in fin evaporator structure.

Water is delivered to a mold 22 of ice maker 13 through a supply valve 23 and an inlet 24. The formed ice bodies are delivered downwardly from the ice maker into a subjacent collecting bin 25 by movement ofa transfer device 26 through the mold in a harvesting cycle upon completion of the freezing of the ice bodies in the mold. A sensing arm 27 is provided for detecting the level of ice bodies in the collecting bin and is associated with a control 28 for automatically preventing further ice body formation when the bin is full.

control 28 includes a drive motor 29 in the form of a timer motor which drives the shaft 30 of transfer device 26 through suitable gears 31, including motor pinion 3la and gear 31b driven by pinion 31a. In the illustrated embodiment, initiation of the drive motor operation is controlled by a thermostat 32 (see FIG. 4) in thermal transfer association with the mold 22 in which the ice bodies 33 are formed. Thus, when the temperature of the mold sensed by thermostat 32 reaches a low temperature, such as 23 F., the switch initiates the harvesting cycle by firstly energizing a mold heater 34 connected in series with the switch between power supply leads L, and L as shown in FIG. 3. At the same time, the motor 29 is energized to commence harvesting operation of the transfer device 26.

Operation of motor 29 also causes a periodic throwing of a gang switch 35 including a first single pole switch 36 connected between power supply lead L and motor 29 for providing a holding circuit to the motor during the defrost operation. Gang switch 35 further includes a second single pole, double throw switch 37 which is normally closed in series with the unit thermostat switch 38 and the parallel combination of compressor 18, condenser fan 39, and evaporator fan 40 connected to the other power supply lead L The defrost heater 41 is connected in series in series with a defrost bimetal thermostat 42 to power supply lead L when switch 37 is closed in series therewith by the initiation of the defrost cycle. Switch 35, as shown in FIG. 2, is arranged to be actuated from motor 29 and gearing 31 through a second set of gearing 43 and a cam 44 adapted to engage the actuating member 45 of switch 35. Gearing 43 may include a pinion 43a on shaft 30, a gear 43b driven by pinion 430, a pinion 43c rotatable with gear 43b and driving a gear 43d. Cam 44 is connected to gear 43d by a clutch 43e. Switch 36 is connected in series from power supply lead L through motor 29 when gang switch 35 is thrown so as to continue operation of the motor during the defrost cycle notwithstanding the throwing of motor holding switch 46 to the open position as shown in FIG. 3 wherein the circuit from the motor 29 through switch 46 to power supply lead L is broken.

As further shown in FIG. 2, the water supply valve 23 is connected in series with a motor controlled switch 47 and a shutoff switch 48 through the ice maker thermostat 32 to the power supply lead L A dry cycle heater 49 is connected in series with power supply lead L and switch 48 to mold heater 34.

Thus, in the normal operation of apparatus 10, the compressor 18, condenser fan 39 and evaporator fan 40 operate in the normal manner under the control of apparatus thermostat 38 to refrigerated chambers 12 and 14. Defrost switch 35 is maintained in the position of FIG. 3 to provide power from power supply lead L, through thermostat 38 to the compressor, condenser fan and evaporator fan. When the collecting bin 25 is less than full, the shutoff switch will be in the position shown in FIG. 3. The normal cycling of the ice maker is effected to make additional ice bodies under the control of the ice maker thermostat 32. Thus, the thermostat switch 32 closes when the ice body formation is completed to energize the mold heater 34 and the ice maker motor 29 which, as shown, are connected in parallel with thermostat 32. Operation of the ice maker motor then effects a throwing of the ice maker holding switch 46 so as to connect the motor 29 through switch 46 between power supply leads L and L to maintain the continued operation of the motor. The ice maker then goes through a normal cycle with the mole 22 being refilled with water at the completion of the cycle by the closing of water valve switch 47 for a preselected period of time.

When the collecting bin becomes full so that the shutoff switch is thrown from the position of FIG. 2 to connect the dry cycle heater in series with the mold heater 34 and break the connection to the water valve switch 47, the dry cycle heater 49 is cyclically energized under the control of the ice maker thermostat 32 which, as shown in FIG. 2, cyclically shorts out the heater 49 so as to cause the ice maker to go through the ice making cycle without delivering water to the mold at the end of each harvesting cycle portion of the operation. The dry cycle heater is energized whenever the ice maker is shut off, i.e., the switch 48 is thrown from the position shown in FIG. 2, and is preselected so that the time required to effect a full dry cycle operation of the ice maker is approximately equal to that required for the normal ice making cycle. The dry cycle heater simulates, during the dry cycle, temperature conditions sensed by the ice maker thermostat which obtain during the normal ice making cycle so as to cause the ice maker to continuously cycle and, thus, provide a clock function for controlling the defrost intervals.

More specifically, when switch 35 is actuated after a preselected number of cycles as controlled by the gearing 31 and 43, cam 44 throws switch 35 from the full line position of FIG. 2 to initiate a defrost operation. Thus, gearing 31 and 43 effectively defines timing means in controlling the operation of the defrost means herein. The throwing of switch 35 firstly de-energizes the compressor 18 by the throwing of switch portion 37 from the series relationship with compressor 18 and to connect the defrost heater 41 across the power supply. Concurrently, the switch section 36 establishes a holding circuit for the motor 29 in parallel with the holding switch 46 and the thermostat 32. As the motor is driven during the defrost cycle, the repositioning of switch 35 back to the full line position of FIG. 2 to terminate the defrosting operation after a preselected period of time is automatically effected by the cam 44.

lllustratively, in one form of ice maker as described above, the gearing and cam were arranged to provide a defrost cycle of 21 minutes. More specifically, the following gear table illustrates the specific timing of the illustrated embodiment:

The motor 29 does" not operate during the ice forming portion of the cycle which is under the control of the ice maker thermostat 32 and, thus, the arrangement, as shown in FIGS. 1-3, permits the use of an ice maker wherein the drive motor is operated only during the harvesting or defrosting cycles as discussed above.

A modified form of ice maker is shown in Us. Letters Pat. No. 3,677,030 issued July 18, 1972 of Duane c. Nichols for an Axially Movable Twist Tray Domestic lce Maker, owned by the assignee hereof. US. Pat. No. 3,677,030 is incorporated by reference herein. In that ice maker, the harvesting of the ice bodies is effected by twisting the tray to free them therefrom and inverting the tray to dump the freed ice bodies into the subjacent bin. The present invention comprehends providing in such an ice maker, as well as in the above described type of ice maker 13, a defrost control which utilizes the single ice maker drive motor both for driving the ice maker mechanism and for controlling the defrost cycle and duration. In such a twist-tray ice maker, the timing of the ice maker cycle is effected by the drive motor and not by a thermostat such as thermostat 32 utilized in connection with apparatus 10.

Thus, as shown in FIG. 6, the twist-tray ice maker apparatus control 128 utilizes an ice maker motor 129 connected in series with a single pole, double throw defrost switch and a parallel connection of the compressor 118, condenser fan 139 and evaporator fan 140 between the power supply leads L, and L The drive motor 129 may take the form of a conventional timer motor. The refrigerator thermostat switch 138 is connected in series with the switch 135 also to the compressor, condenser fan and evaporator fan. As shown in FIG. 6, the moving contact 135a of defrost switch 135 is connected to power supply lead L one fixed contact 13512 is connected to ice maker motor 129 and the other fixed contact 1350 is connected to the thermostat 138. Thus, depending on the throw of switch 135, power supply lead L is connected either to the thermostat 138 or the ice maker motor 129. The water valve 123 is connected in series with the valve switch 147 and shutoff switch 148 in parallel with the ice maker motor 129. The defrost heater 141 is connected in series with the defrost bimetal thermostat switch 42 between contact 135b and power supply lead L Thus, as shown in FIG. 5, twist-tray ice maker control generally designated 128 includes a gear train 143 driving a cam 144 for operating the actuator 145 of defrost switch 135. Gearing 143 is driven from gearing 131 provided for driving the shaft 130 at one end of the tray from the ice maker motor 129.

In normal operation, the defrost switch 135 is in the position shown in full lines in FIG. 6 whereby power is delivered to the evaporator fan 140, compressor 118 and condenser fan 139 through the normally closed thermostat 138. Power is also delivered to the ice maker motor 129 from the connection between thermostat 138 and the parallel connection of the evaporator fan 140, compressor 118 and condenser fan 139, and through the defrost bimetal switch 142 and defrost heater 141 to power supply lead L As the ice maker motor has a relatively high impedance compared to that of the defrost heater, the defrost heater is effectively de-energi zed at this time while the ice maker motor develops the necessary power to operate the ice maker. During one portion of the ice making cycle, as discussed above, water is delivered to the mold and to effect this, the valve switch 147 is suitably closed at the proper time to fill the tray. When the collecting bin is full, the shutoff switch 148 opens to prevent further water delivery and, thus, the ice maker dry cycles.

Conventionally, the cycle of the control 128 provides a harvesting cycle every 2 hours of compressor operation, the motor 129 being operated in the ice making cycle concurrently with the operation of compressor 1 l8. Gearing 143 and cam 144 are arranged to provide a defrost cycle upon completion of a preselected number of such ice making cycles which would include not only normal cycles wherein ice is actually made, but also dry cycles. lllustratively, control 128 may be arranged to provide a defrost cycle of 13 minutes duration every third harvesting cycle. Where the ice making cycle is a 2-hour cycle, the defrost operation would be initiated every 6 hours of compressor running time. As will be obvious to those skilled in the art, different defrosting intervals and durations may be provided by suitable selection of the gearing and cam means as desired.

To effect the defrost cycle, switch 135 is thrown by cam 144 to connect moving contact 135a with fixed contact 135b and break the circuit through thermostat 138 from power supply lead L This places the defrost heater 141 directly across the power supply leads to effect a defrosting operation. At the same time, ice maker motor 129 is effectively energized by a series connection from contact 135b through the relatively low impedance parallel connection of evaporator fan 140, compressor 118 and condenser fan 139 so as to maintain the operation of the ice maker motor. Upon completion of the preselected defrost heating cycle, ice maker motor 129 causes the switch 135 to be thrown to connect thermostat 138 to power supply lead L and initiate further ice making cycles.

Thus, control 128 functions to provide a preselected defrost interval and duration by means of the timing function of the ice maker motor eliminating the need for the thermostat 32 of control 28.

In each of the controls 28 and 128, all of the ice maker and defrost control means may be provided in a single housing for simplified construction and installation. In each case, the defrost cycle is correlated with the ice harvesting cycle so as to avoid affecting the ice body freezing cycle. The control of FIGS. 5 and 6 is similar to the control of FIGS. 14 and similar elements thereof are identified by similar reference numerals except 100 higher.

Each of controls 28 and 128 is simple and economical of construction while yet providing the highly desirable features discussed above.

The foregoing disclosure of specific embodiments is illustrative of the broad inventive concepts comprehended by the invention.

Having described the invention, the embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a refrigeration apparatus having cooling means, means for defrosting the cooling means, mechanism including means for making ice bodies and means operated by a drive motor for harvesting the ice bodies, and means for causing cyclical operation of the harvesting means irrespective of the making of said ice bodies, control means for controlling the operation of the defrosting means comprising: timing means operated by said mechanism only during operation of the harvesting means for initiating operation of the defrosting means upon operation of said harvesting means a preselected number of cycles; and means for maintaining operation of the defrosting means for a preselected period of time after initiation to effect defrosting of the cooling means.

2. The refrigeration apparatus of claim 1 wherein said mechanism includes means for operating said drive motor only during harvesting cycles of said mechanism.

3. The refrigeration apparatus of claim 1 wherein said mechanism includes means for operating said drive motor only during operation of the cooling means.

4. The refrigeration apparatus of claim 1 wherein said means for maintaining operation of the defrosting means comprises means operated by said drive motor.

5. The refrigeration apparatus of claim 1 wherein said mechanism includes a mold and means for controlling a water supply to said mold. and means are provided for causing cyclical operation of said mechanism while preventing delivery of water from said supply to said mold whereby said mechanism dry cycles without making and harvesting ice bodies.

6. In a refrigeration apparatus having cooling means, means for defrosting the cooling means, and mechanism for cyclically making and harvesting ice bodies, means for controlling the operation of the defrosting means comprising: timing means responsive to a preselected number of cycles of said mechanism for initiating operation of the defrosting means; and means for maintaining operation of the defrosting means for a preselected period of time to effect defrosting of the cooling means, said mechanism including a mold and means for controlling a water supply to said mold, means for causing cyclical operation of said mechanism while preventing delivery of water from said supply to said mold whereby said mechanism dry cycles without making and harvesting ice bodies, said mechanism further including means responsive to a temperature condition of the mold indicative of the completion of an ice making cycle for initiating the cyclical operation of said mechanism, a heater for providing a temperature condition sensed by said temperature responsive means simulating the temperature condition during making of ice bodies, and means for energizing said heater when the means for preventing water delivery is arranged to prevent such delivery.

7. In a refrigeration apparatus having an ice maker, means for driving the ice maker through a series of cycles effective to make and harvest ice and cycles ineffective to make ice, and means operated by said driving means for defrosting the apparatus upon operation of the ice maker a preselected number of cycles, with the defrosting operation being initiated only during harvesting operation of the ice maker.

8. The refrigeration apparatus of claim 7 including thermostat means for controlling the cycling of the ice maker, means for cycling the ice maker at times without water delivered thereto to provide a dry cycle operation thereof defining said ineffective cycles, and means for operating the thermostat to simulate a normal ice making cycle operation during a dry operation to cause said preselected number of cycles to include such dry, ineffective cycles.

9. In a refrigerator having cooling means, means for periodically defrosting the cooling means, and an ice maker operated by a drive motor for cyclically making and harvesting ice bodies, said refrigerator including control means for controlling the operation of the defrosting means comprising: thermostat means for controlling the cycling of the ice maker; means for cycling the ice maker at times without water delivered thereto to provide dry cycle operation thereof; timing means operated by said ice maker for initiating operation of the defrosting means as an incident of said ice maker being operated through a preselected number of cycles; means for .operating the thermostat to simulate a normal ice making cycle operation during a dry cycle operation to cause said preselected number of cycles to include such dry cycles; and means for maintaining operation of the defrosting means for a preselected period of time after initiation to effect defrosting of the cooling means.

10. The refrigerator of claim 9 wherein said ice maker includes a mold in which ice bodies are formed and said drive motor effects transferring completed ice bodies from the mold after a predetermined accumulated period of operation of the cooling means, and said timing means effects initiation of operation of the defrosting mcans only during an ice body transferring cycle of operation.

mg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,855,812 v Dated Inventor) WILLIAM J. LINSTRQMBERG It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 8, Claim 8, line 39, after "dry" insert the word -cycle..

sigma-at. ans led this 15th day of April 1.975.

fittest:

V. A -JZL$-& l-L L-L-LQ .zJZ'll-L CUTE-l C. .13502? Commissioner of Patents Attestin; Officer and Trademarks 

1. In a refrigeration apparatus having cooling means, means for defrosting the cooling means mechanism including means for making ice bodies and means operated by a drive motor for harvesting the ice bodies, and means for causing cyclical operation of the harvesting means irrespective of the making of said ice bodies, control means for controlling the operation of the defrosting means cOmprising: timing means operated by said mechanism only during operation of the harvesting means for initiating operation of the defrosting means upon operation of said harvesting means a preselected number of cycles; and means for maintaining operation of the defrosting means for a preselected period of time after initiation to effect defrosting of the cooling means.
 2. The refrigeration apparatus of claim 1 wherein said mechanism includes means for operating said drive motor only during harvesting cycles of said mechanism.
 3. The refrigeration apparatus of claim 1 wherein said mechanism includes means for operating said drive motor only during operation of the cooling means.
 4. The refrigeration apparatus of claim 1 wherein said means for maintaining operation of the defrosting means comprises means operated by said drive motor.
 5. The refrigeration apparatus of claim 1 wherein said mechanism includes a mold and means for controlling a water supply to said mold, and means are provided for causing cyclical operation of said mechanism while preventing delivery of water from said supply to said mold whereby said mechanism dry cycles without making and harvesting ice bodies.
 6. In a refrigeration apparatus having cooling means, means for defrosting the cooling means, and mechanism for cyclically making and harvesting ice bodies, means for controlling the operation of the defrosting means comprising: timing means responsive to a preselected number of cycles of said mechanism for initiating operation of the defrosting means; and means for maintaining operation of the defrosting means for a preselected period of time to effect defrosting of the cooling means, said mechanism including a mold and means for controlling a water supply to said mold, means for causing cyclical operation of said mechanism while preventing delivery of water from said supply to said mold whereby said mechanism dry cycles without making and harvesting ice bodies, said mechanism further including means responsive to a temperature condition of the mold indicative of the completion of an ice making cycle for initiating the cyclical operation of said mechanism, a heater for providing a temperature condition sensed by said temperature responsive means simulating the temperature condition during making of ice bodies, and means for energizing said heater when the means for preventing water delivery is arranged to prevent such delivery.
 7. In a refrigeration apparatus having an ice maker, means for driving the ice maker through a series of cycles effective to make and harvest ice and cycles ineffective to make ice, and means operated by said driving means for defrosting the apparatus upon operation of the ice maker a preselected number of cycles, with the defrosting operation being initiated only during harvesting operation of the ice maker.
 8. The refrigeration apparatus of claim 7 including thermostat means for controlling the cycling of the ice maker, means for cycling the ice maker at times without water delivered thereto to provide a dry cycle operation thereof defining said ineffective cycles, and means for operating the thermostat to simulate a normal ice making cycle operation during a dry operation to cause said preselected number of cycles to include such dry, ineffective cycles.
 9. In a refrigerator having cooling means, means for periodically defrosting the cooling means, and an ice maker operated by a drive motor for cyclically making and harvesting ice bodies, said refrigerator including control means for controlling the operation of the defrosting means comprising: thermostat means for controlling the cycling of the ice maker; means for cycling the ice maker at times without water delivered thereto to provide dry cycle operation thereof; timing means operated by said ice maker for initiating operation of the defrosting means as an incident of said ice maker being operated through a preselected number of cycles; means for operating the thermostat to simulate a noRmal ice making cycle operation during a dry cycle operation to cause said preselected number of cycles to include such dry cycles; and means for maintaining operation of the defrosting means for a preselected period of time after initiation to effect defrosting of the cooling means.
 10. The refrigerator of claim 9 wherein said ice maker includes a mold in which ice bodies are formed and said drive motor effects transferring completed ice bodies from the mold after a predetermined accumulated period of operation of the cooling means, and said timing means effects initiation of operation of the defrosting means only during an ice body transferring cycle of operation. 